1. Field of the Invention
The present invention relates to a drive tool for driving driven members, such as nails, into a driven material using an electric motor as a drive source.
2. Description of the Related Art
For example, a nail driving machine generally uses compressed air as a driving source, and a large striking power can be obtained by reciprocating a piston with the compressed air. In contrast, a tool has been proposed which strikes driven members, such as nails, by reciprocating a striking driver (a striking rod) with an electric motor as a driving source. Since driving the electric motor as the driving source with a direct current power source (a battery) makes connection of an air hose and a device such as a compressor in the case of an air system to become unnecessary, usability and handling property of the driven tools can be improved.
This electric drive tool has a basic configuration in which a drive wheel is rotated with the electric motor as the driving source, and a driver supporting base which supports the driver is strongly pressed against a peripheral surface of the drive wheel, so that a linear movement (a striking operation) in the direction of driving the driver is obtained.
As a technology relating to the electric drive tool, the one disclosed, for example, in U.S. Pat. No. 7,137,541 is publicly known in the related art. The technology disclosed in this Patent Document is configured to achieve a driving operation by getting the drive wheel to rotate in advance in a standby state by activating the electric motor at a moment when one of a first operation to press a contact trip against a driven material to move the same relatively upward and a second operation to pull a trigger-type switch lever (a trigger) with a finger tip is performed, and then by pressing the driver supporting base against the drive wheel at the timing when the other one is performed. According to this technology, activating the electric motor and getting the drive wheel to rotate in advance in a standby state by performing one of the first and the second operations causes a quick driving operation to be achieved at the timing when the other operation is performed.
However, according to the technology in the related art, since the configuration is such that the driving operation is performed by the pull operation of the trigger by the second operation in a state in which the contact trip is moved upward by the first operation, and the electric motor is started and the drive wheel starts to rotate in a standby state by the second operation before performing the first operation, it is preferable to include a third operation as a condition of starting the driving operation in view of prevention of an erroneous operation of the drive tool.
Further, in this kind of drive tool, a driving operation is performed one time when the first operation and the second operation are performed, and for performing a second driving operation and its subsequent driving operations there has been incorporated a continuous shot mode, in which continuous driving operations are performed by once performing an off-operation of the contact trip and by again performing an on-operation (first operation) while the trigger (second operation) is being pulled, and a single shot mode, in which a second driving operation cannot be performed unless off-operations of both the first operation and the second operation are once performed to reset to an initial state every time after the driving operation. Previously, one having a special switchable lever has been provided in order to switch between these operating modes, but a prompt mode switching cannot be performed owing to a troublesome switching operation.
Therefore, it is an object of the present invention to provide a drive tool that can reliably prevent an erroneous operation of the drive tool by allowing a driving operation only when a third operation is performed in addition to the first and second operation and that can realize a mode switching operation without troublesome operations of a lever as conventionally required.